Self-lubricious tool coatings for ecological metal cutting

The ambition of this work is to contribute towards the scientific background and understanding required to enable a knowledge-based design of self-lubricating tool coatings. The strategy is to apply ab initio calculations to identify transition metal oxides, so-called Magnéli phases, that possess low friction coefficients and therefore can act as solid lubricants, and to alloy TiAlN with these elements by sputter deposition. These Magnéli phase oxides are expected to form on the surface of the as-alloyed TiAlN tool coating during metal cutting processes and provide lubrication without the necessity to use additional, fluid lubricating agents. Thus, more precisely, the objective of this work is to contribute towards understanding the correlation between composition, structure, elastic properties and decohesion energies of transition metal Magnéli phase oxides, namely vanadium, tungsten and molybdenum oxides, and correlate these with the electronic structure thereof. Furthermore, as the second step, the follow up objective is to contribute towards understanding the correlation between composition, structure and mechanical properties of cubic TiAlN alloyed with such Magnéli phase forming elements. Here, tungsten is chosen as a demonstrator, therefore cubic TiAlN–WNx thin films are investigated.